Battery modules are composed of multiple battery cells. Effective strapping is essential to ensure stable operation under complex operating conditions and prevent displacement and collision. Much like steel bars in a building, they securely connect the various components and make the overall structure as solid as a rock. In the field of battery module strapping, steel strap and PET strap have emerged as the two most popular strapping materials. Each has unique properties and advantages, playing an irreplaceable role in the new energy industry.
Steel Strap：
(I) Basic Characteristics of Steel Strap
Steel strap, a common metal strapping material, has a long history of industrial use. It is a narrow, long steel strip produced by various rolling mills and typically supplied in coils. Steel strap has high tensile strength, enabling it to withstand significant tension without breaking. Like a sturdy chain, it provides a secure bond to the battery module. Furthermore, it has a certain degree of elongation, allowing it to adapt to a certain degree of deformation while maintaining strength, ensuring that even minor dimensional changes in the battery module do not compromise its strapping effectiveness.
Steel strapping excels in dimensional accuracy, with tight tolerances on thickness and width, meeting high-precision production requirements. Furthermore, the steel strapping's surface quality is excellent-smooth and flat, free of noticeable defects and blemishes-which not only facilitates subsequent processing but also reduces wear on the battery module surface. Furthermore, steel strapping is easy to process and can be formed into various shapes and structures through various methods, such as stamping, bending, and welding, to suit different battery module bundling requirements. This process also saves material and reduces production costs.
(II) Application of Steel Strap in Battery Module Bundling
The use of steel strapping in battery module bundling requires specific processing and operation procedures. Typically, the steel strapping is pre-shaped and processed into a metal frame of a fixed length and width based on the size and shape of the battery module. This process is like custom-making a sturdy armor for the battery module, ensuring that the metal frame fits snugly to the module's contours.
Then, with the help of assembly equipment, the processed metal frame is used to bundle and reinforce the battery module. Using specialized equipment, steel strapping is tightly wrapped around the battery module and secured, firmly securing the battery cells and preventing them from shifting or shaking during use. The entire process requires precise operation and strict quality control to ensure the strapping meets specified requirements, providing a reliable guarantee for the safe and stable operation of the battery module.
PET Strap：
(I) Unique Properties of PET Strap
PET strapping, or polyethylene terephthalate strapping, is a new type of plastic strapping material that has emerged as a leader in the battery module strapping industry. Its surface and edges are exceptionally smooth, like carefully polished satin, providing a velvety feel. This feature eliminates the need for gloves during the strapping and unbundling process, improving efficiency while avoiding the inconvenience of gloves. Furthermore, PET strapping has a melting point of 260°C, making it stable even in high-temperature environments and resistant to deformation or melting. Its flame retardancy and flame resistance rating reaches V0, meaning it can resist the spread of flames, slow combustion, or self-extinguish upon contact with a fire source, providing reliable fire protection for battery modules, like a fire-resistant armor.
Furthermore, for the same weight, PET strapping is six times longer than steel strapping. This advantage makes PET strapping more economical to use, saving companies significant material costs. Furthermore, its light weight facilitates handling and storage, reducing logistics costs.
(II) PET Strap Operation Process for Battery Module Bundling
The simplicity of PET strapping is one of the reasons it is so popular among companies. To bundle battery modules, simply wrap the PET strap around the module. Then, using an electric or pneumatic strapping machine, tighten, lock, and cut the straps with a single click. The entire process is as simple as using an automatic stapler, making it easy for even inexperienced operators to master. Furthermore, PET strapping can be heat-welded, using a snap-free lock. This connection method is not only simple to use but also secure, effectively preventing strapping failures caused by loose fasteners. Furthermore, heat-welding also ensures a smoother connection, preventing abrasion to the battery module casing or cell surface, further enhancing battery module safety.
A Comprehensive Comparison of the Two
(1)Cost Comparison
In terms of material cost, PET strapping offers a clear advantage. Because PET strapping can be six times longer than steel strapping for the same weight, and its raw material cost is relatively low, using PET strapping can reduce packaging costs by 60-80%. This can result in significant long-term savings for large-scale battery module manufacturers, significantly alleviating cost pressures. While steel strapping may have a lower cost per length, its greater weight means that more steel strapping is required to achieve the same strapping effect, resulting in higher overall material costs. In terms of equipment cost, PET strapping machines come in two types: electric and pneumatic. Both are lightweight and relatively affordable. Steel strapping, on the other hand, requires specialized assembly equipment for shaping and strapping. This equipment is often expensive, with high procurement and maintenance costs, further increasing the overall cost of using steel strapping.
(2)Safety Comparison
PET strapping offers significant advantages in terms of safety. Its smooth surface and edges, without sharp corners, prevent scratches on the battery module casing and pose no risk to operators during the packaging and unpacking process, providing a relatively safe working environment. However, when steel strapping is tightened with steel strapping buckles, arches or protrusions form on the strap. Over time, these protrusions can abrade the battery module casing or even puncture the battery cells, potentially causing serious safety hazards such as short circuits and fires.
(3)Operational Comparison
PET strapping is far easier to operate than steel strapping. PET strapping can be tightened, locked, and cut with a single click using an electric or pneumatic strapping machine. The entire process is simple and quick, even for beginners. Steel strapping, on the other hand, requires pre-formed metal frames of fixed lengths and widths. These are then assembled with assembly equipment to secure the battery modules. This involves multiple, complex steps and requires specialized technicians. This requires high skill levels, takes a long time, and is less efficient.
(4)Durability Comparison
Under normal use, steel strapping, due to its high strength, offers superior durability, withstanding significant tension and impact without breaking. However, a significant weakness of steel strapping is its susceptibility to rust. Once rusted, its strength and corrosion resistance are significantly reduced, shortening its service life. In contrast, PET strapping is moisture-resistant, rust-resistant, waterproof, and corrosion-resistant, ensuring stable performance in a variety of harsh environments. Although the performance of PET tape may be affected in special environments with extremely low temperatures, high temperatures, high humidity, and chemical corrosion, its durability is sufficient to meet the needs of battery module bundling in most common application scenarios.
Acey Intelligent specializes in providing one-stop solutions for semi-automatic/fully-automatic assembly lines of lithium battery packs used in ESS, UAV, E-Bike, E-Scooter, Power Tools, Two/Three Wheelers, Etc. In Addition, we provide a complete set of battery pack assembly equipment, such as Cell Grading Machine, Battery Sorting Machine, Insulation Paper Sticking Machine, CCD tester, Manual/Automatic Spot Welding Machine, BMS Tester, Battery Comprehensive Tester and Battery Pack Test System, etc.
